40 Featherweight with Amal Concentric Carb

[Boatdrew62]

Hello everyone,
I just became the proud owner of a 1977 40 Featherweight. According to what I've read, it's supposed to have a Bing carb but has been replaced with a new Amal Concentric. I'm mostly wondering if I can adapt this carb to work and if so is there jet modifications and other setting I should change. The story was that the previous owner was told that Bing parts are no longer available. The engine number is, GF2396AA7. Any advice would be greatly appreciated...

[Keith.P]

I picked up a GF the other week with Bing carb and they do seem to be a bit fragile, plus the cover has a habit of falling off.
Not knowing if the carb is even suitable for a seagull, let alone what the settings are, I would put a seagull carb back on it, either get an original bing carb, or even a villiers with a 25:1 needle.

[Charles uk]

Could you post a picture of your carb, as I wasn't aware that a concentric was available that would fit on a Seagull 40, the carb number would help a lot.

[Boatdrew62]

Thankyou for getting back to me. It's dark here now so tomorrow I'll try to post a picture or two as well as locate the carb number. Are the original Bing carbs that hard to come by?

[headdownarseup]

Just wondering if this carb might be a later amal 400 series (possibly a 416) with a plastic insert fitted inside the stub fitting. I've seen this before on a few 40 series motors.

It has been mentioned in the past that any motor with the letter G within its serial number might suggest that a Bing was originally fitted.
My own EGF (basically a modern type featherweight) has a Bing fitted, but the villiers carb will also fit and there are plenty of these carbs around. The only thing to watch out for with the villiers carb is that the correct fuel needle is fitted to allow you to use a 25:1 fuel ratio if that's what you want to do. However, as your motor was manufactured in 1977 ideally it should be running at 10:1. Most seagulls made AFTER 1978 were slightly re-designed to run with LESS oil in the fuel mix (25:1)

As Keith has pointed out already, the Bing carbs have a nasty habit of the square inlet cowling suddenly dropping off. (they're basically a snap fit to the outside of the carb). Float bowls are sometimes available (they crack and leak) as are the choke flap assemblies which after nearly 40 years will have become very brittle by now.

If it turns out that your motor has the later 416 carb fitted, then it should be pretty much good to go as it is on 25:1.

Pics will help us to identify what you have.


Jon

[Oyster 49]

Amal concentric are available as 600 series and 900 series. Both are aimed at mid range classic bikes. My Triumph 500 twin had Amal 600 series from 1967 onwards.

Far too big to fit on a seagull, somebody obviously fitted it as they had it around. I would buy a correct carb off ebay for £20 and know it is right.

[Boatdrew62]

Thanks guys,
It turns out I do have a 416 Amal, I took a couple of photos but am too dense to figure out posting them. It sounds like from what headdownarseup has said and what I found upon further reading, that I should be ok.
One other question... If I were using the engine in salt water for prolonged periods of time, should I be using 10-1 ratio or is 25-1 ok still...

[Charles uk]

25 : 1 with a 95 0r 100 jet.

[headdownarseup]

Sorry to say it guys, but i had a sneeky suspicion that this might be the case.
As i said before, i have seen this once or twice on the 40 series motors.



Before venturing out into the salty stuff, try out your motor in a test bin with the 400 series carb fitted. Make sure that the engine starts and performs well under all throttle settings without faltering, coughing, spluttering or miss-firing. 30 mins at half/full throttle should do it. Once cooled down a bit, remove the spark plug and see if there are any tell tale signs on the electrode that might suggest that there would be an adjustment needed to the fueling or amount of oil in the mix.
Sometimes you can never really tell for sure whether an "alternative" carb is good enough for your motor.
Plenty of villiers carbs about if you feel the need to revert back to something more appropriate.
Bing carbs, although being the standard fitment for your motor, are becoming sought after. That said they are known for their weaknesses as mentioned before and unless you can find a complete Bing carb with nothing wrong with it, you may be better off with a Villiers as a tried and tested alternative.
Try the motor out as you have it there before deciding on swapping carbs. You never know, it might be quite happy as is.

Let us know how you get on.
Plenty of advice here

Jon

[Charles uk]

A 416 on a 40 series motor was a standard fitting post mid 79, Jon, so not really an "alternative" carb!

Bings were only used 77 to 79.

[Boatdrew62]

Thanks again for all the help guys...will definitely keep you posted.

[headdownarseup]

Charles
Yes i know the 416 was used on later 40 series, Curlew springs to mind as one of those using this carb.

From what i've seen over the last 10 years, occasionally the odd older model 40 crops up with a 416 when originally it would have had either a villiers or bing.
This particular motor in question would appear to be one such motor.
To date i've seen a handful of them, so nothing entirely out of the ordinary. Similar to when a 46n gets replaced with a 416 on some of the 102's or centuries.
It is what it is.

Jon

[headdownarseup]

Question for Charles here.
Can you decipher this engine serial number please.
EGF221GG1 (my own EGF) and tell me what the date corresponds to. I'm curious


Jon

[Charles uk]

E = electronic ignition
G = Bing carb
F = 64 cc series
221 = serial number
GG1 = July 81

Which makes it a strange one as Seagull's own paperwork says Bings only used between 77 & 79 then they say EGF Model 45, 82 to 84, very strange!

Curlews were only fitted with the Amal 418.

[Keith.P]

I got a GFP the other week.
I found this out.

G = GUMMED up bing carb.
F = F!&%ED motor
P = PARTS only good for.
1421 = serial number
NN6 = December 1976

It's good to help.